Garmin Diamond DA40, Maintenance Manual

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G1000/DA40 System Maintenance Manual Page 2-11
190-00303-03 Revision 6
2.4 Electrical Power Distribution
Distribution of power to the G1000 occurs on three buses:
Essential Bus: The ‘Essential’ bus is tied directly to the aircraft battery via the master switch. When the
master switch is turned on, power is immediately supplied the ‘Essential’ bus. The ‘Essential’ bus is tied
via a relay switch to the ‘Main’ aircraft bus. There are two circuit breakers on either side of the relay,
combined with a single diode, allowing the battery to be charged by the alternator. Only equipment
deemed essential for safe flight is connected to this bus.
Main Aircraft Bus: The ‘Main’ bus receives power from the aircraft battery when tied to the ‘Essential’
bus. After the aircraft engine is started, the alternator supplies power to the aircraft ‘Main’ bus, and to the
rest of the system. In the event of an alternator or other power failure, the ‘Essential’ bus can be isolated
with the ‘Essential Bus’ switch. This causes the ‘Essential’ bus to revert to battery power. Only the MFD
receives power from the ‘Main’ bus.
Main Avionics Bus: A ‘Main Avionics’ bus is tied to the ‘Main’ aircraft bus via the ‘Avionics Master’
switch and switch relay. Only the #2 GIA 63 and the GMA 1347 are connected to this bus.
Figure 2-8. G1000/DA40 Electrical Distribution